U.S. Pat. No. 4,981,097 discloses a system for closing an oil leaking rupture from an oil holding tank disposed in an oil carrying vessel disposed in water. This system includes a pillow storage container which is fixedly secured to the vessel above a hole in the deck of the vessel which overlies an open upper end of the tank and communicates therewith. The container and the tank are interconnected in an air tight fashion. The container can be pressurized and releasably contains a plurality of oil absorbent pillows. The container has at its open lower end a releasably disposed member disposed in the hole above the tank which, prior to release of the member, prevents the pillows from falling out of the container into the tank.
When the tank is ruptured below the water line, the floor of the container is automatically opened, and the pillows fall by gravity into the tank. The pillows fall downwardly though the oil by action of gravity and, upon reaching the rupture, seal off the rupture and prevent further loss of oil.
Subsequent to the issuance of U.S. Pat. No. 4,981,097, applicant conducted a series of experiments with this system. Applicant discovered that the pillows described in this known system will not function efficiently unless, as explained in the above identified copending application, these pillows, in addition to being oil adsorbent and impervious to water, also exhibit a density heavier than oil and lighter than water.
During this series of experiments, applicant also discovered that the use of gravity force alone, in causing the pillows to fall by gravity into the ruptured oil tank was not efficient because the pillows fell relatively slowly into the tank. However, when the gravitation force was substantially augmented by an additional downwardly directed force, the pillows were discharged into the ruptured oil tank with substantially increased speed, thus providing the desired increase in efficiency.
Applicant also discovered that this efficiency could be further increased by decreasing the vapor pressure in the upper end of the ruptured tank.